This invention relates to automatic cap closing machines, and more particularly to machines for closing flip-top caps, which machines are easily adjustable to accommodate different size caps and test the cap covers after they are closed to insure that they can be reopened and closed with the proper amount of force.
Recent advances in packaging have introduced "flip-top" caps which may be used on toothpaste tubes, shampoo bottles, and similar devices. A flip-top cap is a unitary plastic part which has a hollow barrel part which may be fastened to the top of a toothpaste tube, for example. The top of the barrel has a cover hinged thereto in order to flip between two positions to open and close the top of the barrel.
The flip-top cap has to be an extremely low cost item owing to the high volume often required by industry. Also, many of the products sold in the packaging with flip-top caps are of relatively low cost, so that even a small fraction of a cent of excess cost for the cap might raise the retail price of the product sufficiently high to destroy the market for the product.
Usually, the flip-top caps are molded in a relatively large mold having in the order of forty to fifty or more cavities. The geometry of the mold cavities produce flip-top caps with the cover in a fully open position. Before the cap may secure the product in the tube, the cover must be flipped over the barrel to the closed position. This should be done to multiple caps simultaneously, rather than to each cap sequentially, to save time and avoid increasing the cost of the cap. Heretofore, cap closing has been accomplished primarily by the combination of an action mold for mechanically pushing the cover up from the mold, an air blast for moving the cover up from the mold, an air blast for moving the cover most of the way toward the closed position, and a final mechanical device for fully closing the cove. However, action molds are expensive and air blasts cool the mold and flip-tops, thereby increasing the chance that the hinge of the flip-top will crack or break during the closing process.
Frequently with the prior devices, the caps are not fully closed, so they reopen seconds later. Detection of incompletely closed caps usually depends on visual inspection. Also, since the closing process occurs while the caps are still in the mold, the mold cycle time is increased, thereby tying up the mold to reduce the output per cavity and make the entire process more costly.
One solution to these problems has been provided in Applicant's U.S. Pat. No. 4,847,988. With the invention disclosed there, numerous caps can be quickly and efficiently closed in a low-cost manner.
Yet even when all of the caps are closed, quality control problems derived from the initial molding process may remain. The cap covers are locked in place due to a friction fit between the cover and the barrel, and sometimes with a plastic flange on either the cover or barrel that engages or snaps into a depression on the other part of the cap. If molding results in caps which require too much force to reopen, the ultimate consumer is inconvenienced and displeased, and sales usually decrease. If molding results in covers which are locked too loosely, the cover may open prematurely during product assembly, shipment or during use by the consumer, resulting in jams in the capping equipment during bottle filling or spillage during shipment or consumer use. In each case, the manufacturer is faced with product returns, financial losses, and potential loss of consumer goodwill.
To combat these problems, present technology requires quality control personnel to periodically spot check small samples of production runs of caps. Usually, it is too expensive to check each cap. Therefore, overall cap quality is judged based on statistical assumptions rather than on the testing of each cap.
Additional problems and costs occur when it becomes necessary to close caps of a different size. For example, a large shampoo bottle will generally use a cap having a larger diameter and height than a small shampoo bottle. Product manufacturers which package their products using flip-top caps also frequently change the configuration of their caps, for either functional or marketing purposes. With cap-closing machines like the one described in U.S. Pat. No. 4,847,988 and most other machines, this means that either an entirely different cap closing machine must be used or a substantial number of different size components must be substituted in the cap closing machine to accommodate the different size caps. In particular, the component which receives the open cap must be changed to either a wider or more narrow opening, and the floor upon which the open cap sits during the cap closing process must be raised or lowered, to handle the new size caps. This changeover of parts results in substantial down time for the cap closing machine, higher costs for the various size machine components which must be stocked, purchases of several different size cap closing machines, and ultimately, higher manufacturing costs which are reflected in higher costs to the consumer.
One existing machine uses an adjustable ring-shaped track and dial pockets to accommodate a range of different size caps. However, the track must be manually set in the proper position for each different size cap, and the caps are retained in the dial pockets merely with an L-shaped stop and a small hold-down slide, both of which loosely confine the cap barrel between them. This device may keep the caps from moving laterally, but the caps are not clamped or firmly held down in the pocket, which precludes testing the covers for proper opening and closing forces while the caps are in the dial pockets.
Accordingly, it is an object of this invention to reduce the engineering and manufacturing costs involved in operating a cap closing machine. Yet another object is to provide a cap closing machine capable of easily adjusting to a range of different size caps without component changes and without an entire change of machine.
A further object is to provide an effective and efficient means for testing flip-top caps to determine whether their covers open and close with the proper amount of force, and to avoid the need for costly and often ineffective spot-checking of caps.